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By Grant R. Brown

The report provides guidance for determining those environmental impacts associated with the surface mining of steeply pitching coal seams. In addition to the environmental impacts, four additional issues are addressed, namely (1) Time and motion studies of those coal mining systems employed in mining seams which pitch in excess of 250, (2) Assessment of those mining techniques, (3) Development of rationale for the mining methods employed, (4) Identification of the reclamation practices and determine whether these practices were in compliance with appropriate Federal and State regulations. Five surface mines located in three geologically distinct basins of the United States were analyzed during the period of August through November 1979. The three basins include the Hanna Basin of Wyoming, the North Park Basin of Colorado and the Southern Anthracite Field of Pennsylvania.

Jan 1, 1980

By Y. Mitani, F. Vallier, T. Esaki

Shear-flow coupling tests are conducted using an original apparatus, and a shear-flow coupling model using Geographic Information System (GIS) is developed in order to evaluate shear-flow coupling properties of a rock joint. Shear-flow coupling tests indicate that the hydraulic conductivity of joint once decreases, and then rapidly increases at the shear displacement near the peak shear stress. The proposed model simulates the test results relatively well. However it indicates that it is difficult to apply the local ‘cubic law’ model in the initial shear stage, in which the change of selective flow path is remarkable. Scher-Fliess-Kopplungsversuche werden mit einem neuartigen Versuchsgerät durchgeführt und mithilfe von Geo-Informationssystemen (GIS) gedeutet, um so ein Modell für die Scher-Fliess-Kopplung in Gebirgstrennflächen zu entwickeln. Die Versuche zeigen, dass die hydraulische Leitfähigkeit zuerst abnimmt, dann aber schnell wieder zunimmt sobald die maximale Scherfestigkeit erreicht ist. Das vorgestellte Modell bildet die Testergebnisse relativ gut nach. Es zeigt auch, dass es schwierig ist, das lokale Cubic Law im Initialstadium der Scherbeanspruchung anzuwenden, in dem die Variationen selektiver Fliesswege gross ist. Les essaies hydro-mécaniques couplés en cisaillement sont réalisés grâce à un appareil éxperimental prototype et un modèle de couplage hydro-mécanique utilisant le S.I.G (systeme d'information géographique) développé dans le but d'évaluer les propriétés hydro-mécaniques des joint rocheux. Les résultats indiquent que la conductivité hydraulique des joints décroit puis augmente rapidement en se rapprochant du pic de cisaillement. Le modèle proposé simule relativement bien les résultats expérimentaux ; mais indique également qu’il est difficile d’appliquer localement la loi cubique au début du cisaillement où, les changements d’orientation dans le réseau d'écoulement sont considerables.

Jan 1, 2003

By H. H. Fairfield

THE production and inspection of the materials of war involves thousands of observations. Logical action is generally based on the interpretation of many observations. The success of such action depends upon the accuracy of the observations and the soundness of the interpretation placed upon them. There are countless instances where the observer 'sees but perceives not'; that is, the significance of a group of observations is lost, due either to faulty interpretation or to no interpretation at all being placed on the results. This condition is being partly corrected in the United Kingdom and the United States (1) by the promotion of certain principles by Ordnance officials. The term Quality Control has been adopted to describe a system of studying and controlling industrial products by methods of handling observations. In these pages an attempt is made to outline in a non-technical manner some of the ideas used in the handling of observations. Of course the authenticity of the observations determines the worth of any decisions based on them. No matter how brilliant is the theory built on unreliable sampling, it is usually of little practical value. n some fields it is almost impossible to obtain observations free from bias. Let us suppose that observers of speed in miles per hour were available for judgment: (a) a bystander, (b) a motorcycle policeman, and (c) a motorist accused of speeding. The bystander might be unbiased but probably would be very inaccurate. The motorist is usually biased on the low side. The policeman is the only qualified observer and, if over-zealous, he might be biased on the high side. Conclusions drawn from large numbers of biased observations naturally would be of little value.

Jan 1, 1943

By Harry Schnabel

A 6200 m² cement deep soil mixed (CDSM) wall was constructed for an addition to the Museum of Fine Arts in Boston, Massachusetts. The addition was located along the east side of the existing museum within an existing courtyard and in the area of a recently demolished structure. The basement for the new addition extended up to 9.1 m below the floor slabs of the adjacent buildings. The adjacent buildings are supported on a variety of foundations including; shallow spread footings on alluvial sand deposits, low capacity piles bearing in the alluvial sands and Boston blue clay, and caissons bearing on the alluvial sands and clay. Groundwater was less than one meter below the top of the CDSM wall. The new addition was founded on shallow foundations in the desiccated crust of the Boston Blue Clay. The CDSM wall was selected as the most economical means to control deep seated ground movements, limit movements of adjacent structures, and inhibit groundwater flow into the excavation. Braces and a continuous wale were used to support the CDSM wall where it was located adjacent to structures. Tiebacks were used where there were no structures. Other geotechnical construction at the site included: ? Jet grouting (JG) to improve the ground and provide an impervious subgrade layer at the west end of the addition, ? Concrete pier underpinning was used to support an existing structure on the west end of the site, and ? A secant pile wall using alternating drilled shafts and jet grout columns was used for earth support and a barrier to groundwater flow to allow for the installation of a storage tank at the south end of the site. Inclinometers, total station surveying, vibrating wire strain gauges on the braces and wales and load cells on the tiebacks were used to monitor performance of the excavation support system. The excavation support system performed better than required limiting lateral movements of the adjacent structures to less than 13 mm and vertical settlement to less than 8 mm. No settlements or movement were detected during the construction of the wall. Lateral movement of the CDSM wall was typically below 15 mm with the maximum movement occurring near subgrade.

Jan 1, 2011

The Beginnings of Mineral Processing Research in Canada - A Short Account

Sep 13, 2010

By P. C. -H. Rhee, H. -G. Lee, J. -H. Choi, D. S. Kim, S. -B. Lee

In order to predict the composition of inclusions and to ascertain a method to prevent inclusions from forming in liquid Fe-16 mass Cr alloy, a thermodynamic database was developed through a quantitative determination of thermodynamic relationships of Cr-Al-Si-Mn systems in the liquid Fe alloys. Applications of the databases to the prediction of Mn/Si complex deoxidation with Alin Fe-16 mass Cr alloy were demonstrated in succession. The electromagnetic levitation technique using a cold crucible was employed to separate inclusions from liquid metallic alloys completely and to prevent any contamination from surroundings. Various interaction parameters in the liquid Fe-16 mass per cent Cr alloy system were determined; these are: [eAl(Fe)Cr= 0.19/T, rAl(Fe)O,Cr= -0.01, rAl(Fe)O,Cr= -0.00013, eS1Cr(Fe)= -0.38/T,rSi(Fe)O,Cr= 0.007, rO(Fe)Si,Cr= 0.0044, rA1(Fe)Si,Cr= -0.0075, rSi(Fe)A1,Cr= -0.0078, rSi(Fe)Mn,Cr= 0.005, and rMn(Fe)Si,Cr=0.01.] An improved database, utilizing interaction parameters for molten metal determined in this study, and the Fact Sage slag database of the MnO-SiO2-Al2O3-CrOx-MgO system were used for thermodynamic calculations. These were carried out under various thermodynamic conditions, and results were compared with experimental data of Si/Al, Mn/Si, and Mn/Si/Al deoxidation equilibria. With the abovementioned results, together with experimentally obtained data, thermodynamic conditions were determined, in particular Mn and Si contents, under which liquid inclusions form in liquid Fe-16 mass per cent Cr alloy. The critical Al content in liquid Fe-16 per cent Cr alloy, above which solid inclusion of corundum phase ((Al,Cr)2O3) formed, was as low as 10 ppm. This indicates that extreme care must be taken in controlling the Al content in the metal to avoid formation of solid corundum phase ((Al,Cr)2O3) inclusion. The compositional change prediction of inclusions, which originate from slag entrapment and by Ca addition, was demonstrated by use of the alloy database optimized through this study, and the Fact Sage oxide database. For Si-deoxidized Fe-16 per cent Cr alloy, high Si and low basicity of slag are effective to obtain liquid inclusions. For Al-deoxidized Fe-16 per cent Cr alloy, it is important to keep the Si content lower than 0.1 per cent and it is required to add Ca. Keywords: inclusion, thermodynamic simulation, deoxidation, Fe-16 per cent Cr alloy,stainless steel, interaction parameter, cold crucible

Jan 1, 2004

By D. Harrington

Educational campaigns conducted by the manufacturers of explosives, the Bureau of Mines, mining companies, and safety organizations have contributed greatly in reducing accidents caused by explosives arid blasting. Despite these campaigns and the dissemination of information, accidents from explosives and blasting continue to be the direct cause of scores of fatalities and hundreds of nonfatal accidents annually, not only in the mineral industry but essentially wherever explosives are used. The experience of many mining companies and other users of explosives has proved that accidents from explosives can be prevented or averted by the proper training of employees in the handling and using of explosives and by the enforcement of definite rules and instructions for their use. Unfortunately, throughout the years numerous false impressions and ideas have grown up and around the use of explosives. Many of these can be traced back to the manner in which the users of explosives were originally taught, if instructed at all; and as with many types of misinformation in nearly all walks of life, those false ideas are decidedly persistent and being so cause much damage. Many if not most of the users of explosives gained their knowledge of explosives and blasting by watching others and more or less "absorbing" the procedures and thrones of the other fellow, who acted unconsciously as teacher or instructor. A study of explosives accidents reveals the results of such "teachings" when the causes of the accidents are determined, and as might be expected the results very often are far from good. One of the most persistently erroneous impressions or ideas is concerned with the burning rate of safety fuse. Many men with

Jan 1, 1944

By T. H. Chan

As the University of Hong Kong and their advisors planned their new Centennial Campus it became clear that they would have to re-provide existing water reservoirs on an adjacent site with new salt water reservoirs located underground in two new caverns. The existing reservoirs are owned by the Water Supplies Department who provide salt water for sanitary flushing and a separate potable water supply for regular use. Although underground reservoirs had not previously been adopted locally, the planning has been completed to a tight schedule and the construction is well advanced. The need to preserve historic buildings imposed constraints, as did the requirement to minimise potential construction nuisance for the local community and environment. This paper presents the background to the project and the work carried out to develop an innovative, sustainable and environmental acceptable solution. Construction progress to date is also presented.

By Sofoulis J

In the Archaean of the Kalgoorlie-Norseman area, the layered rocks have been subdivided into two sequences, both containing basic igneous rocks and sediments. The lower sequence is distinguished by the presence of acid volcanic flows and large acid sills. The upper sequence is unconformable on the lower one.In some areas, clastic sediments become coarser and pass into conglomerates. Th:s passage is accompanied by thinning of the beds.These features and their distribution suggest a basin of subsidence flanked by areas of shore-line conditions.Repeated igneous activity, including vulcanism, has occurred along the flanks of this basin. These different igneous and sedimentary environments have played an important part in the primary distribution of metals.A chronology of all basic and acid igneous activity, as well as sedimentat:on, has been established for the Precambrian of this area.INTRODUCTIONThe subdivision of Archaean rocks into those of basic igneous or of sedimentary origin has formed the basis for the nomenclature appearing in past literature. These subdivisions were distinguished as greenstones (predominantly basic igneous rocks) and whitestones (predominantly sediments), and it was generally accepted that the greenstones were stratigraphically lower in the sequence than the whitestones.Recent studies show that, between Kalgoorlie and Norseman, basic igneous rocks interfinger with and pass laterally to sediments, and that basic volcanic rocks occur at different stratigraphic levels. Younger Precambrian. units are also...

Jan 1, 1965

By D. P. Roberts

This investigation aimed to simulate the experiments performed by Nic Gay (Gay, N.C. 1976. Fracture growth around openings in large blocks of rock subjected to uniaxial and biaxial compression. International Journal of Rock Mechanics and Minining Sciences and Geomechical Abstracts, vol. 13. pp. 231-243) on fracture growth around openings in blocks of rock subjected to uniaxial and biaxial compression, using the Elfen discrete element code. The results of the physical experiments indicated a number of trends that were successfully replicated in the numerical simulations, including crushing ahead of the face, the formation of a sub-vertical tensile fracture at centre-span, the formation of groups of fractures originating from the crushed face zone, the formation of large corner-to-corner fractures which precede sample failure, and linking of slot corner and sample corner fractures leading to sample failure. In addition, other features were apparent that were not reported by Gay. It is believed that these took the form of conjugate shear fractures (as reported by Gay in a previous paper) and other features that may have been altered or inhibited by the presence of pre-existing structure in the physical samples. It was found that the samples, though nominally made up of the same rock type, must have had significantly differing properties. The presence of pre-existing structures may have contributed to this discrepancy. Strain measurements from the physical experiments were reasonably well matched, except where the gauge lay directly in the path of advancing fractures.

Jan 1, 2012

There is a saying, ?If it moves, it vibrates.? This is especially true in our modern industrial environments, where workers use powered tools, machinery, vehicles, and heavy equipment. How workers are affected by these elements of the industrial working environment is a concern of health professionals, govern­ments, and scientists around the world. How to adequately assess the effects of human vibration exposure is an equally important issue. The human body comprises a dynamic structure that is living, intelligent, and complex. Consequently, it is not unreasonable to consider that exposing the body to an array of vibration environments would result in outcomes that are not necessarily simple or easily predictable. Sensations caused by vibration may include nausea, annoyance, discomfort or pain, and exhilaration or pleasure. Many factors contribute to the effects of vibration on humans, including the characteristics of the motion and the exposed indi­vidual, the activities of the exposed individual, and various elements of the environment. There have been attempts to summarize the effects of occupational vibration exposures by simply recommending the avoidance of certain frequencies of vibration or by providing a graphical method, i.e., a single curve displaying all human responses to all frequencies. However, such efforts have not withstood the scrutiny of scientific research and analysis. Thus, attendees and participants at this professional gathering now have the rare opportunity to benefit from the technological advances and new scientific research to enhance their understanding of human responses to vibration that suggest more than a simplistic approach. In the tradition of the First American Conference on Human Vibration (1st ACHV) held in Morgantown, WV, June 2006, the 2nd ACHV provides a forum for scientists, engineers, medical doctors, industrial hygienists, and educators to learn and advance research and education in the specialized area of human body vibration. The conference was organized by the Mechanical and Industrial Engineering Department, University of Illinois at Chicago, with support from the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory. As with the first conference, the 2nd ACHV provides the unique opportunity to learn about the current activities of peers and colleagues and to exchange information on topics of interest such as human response, human modeling, experimental design, sensors, new technologies, and epidemiological studies of human responses to hand-transmitted and whole-body vibration. The conference organizers hope that the publication of these conference proceedings continues to foster new research and technological advances to reduce health hazards associated with occupational vibration exposures.

Jun 1, 2009

By R. S. McClain

The Federal Bureau of Mines investigated residues from aluminum plants, to determine if carbon could be removed by flotation while recovering fluorine and aluminum compounds for recycling to the reduction process. This publication summarizes studies on samples representing three types of plant waste products, supplied by three aluminum-producing companies. Samples of flue dust, pot skimmings, and pot linings from the various plants all responded to a simple turpentine flotation scheme to reject 90 to 97 percent of the carbon. Aluminum compound recoveries ranged from 42 to 94 percent on the flue dust, were about 95 percent on the pot skimmings, and ranged from 75 to 89 percent on the pot linings. Fluorine recoveries from the same samples ranged from 35 to 63, 92 to 95, and 77 to 86 percent, respectively. The pot linings contained soluble salts of aluminum and fluorine which were recovered by precipitation with sodium aluminate and carbon dioxide gas. Composites of residues from each plant responded to flotation much the same as the individual samples. Aluminum is produced by the electrolysis of alumina in a molten cryolite bath. The electrolytic reduction cell consists of a carbon-lined box containing a pad of molten aluminum which serves as a cathode, a carbon anode, and an electrolyte of molten cryolite in which the alumina is dissolved. Alumina is reduced to aluminum at the cathode, and carbon is oxidized at the anode.

Jan 1, 1961

This paper gives a general description of mining operations at the Mount Morgan Open Cut. Certain features such as blast hole diamond drilling, which may be of particular interest, have been described in detail. The paper is covered by the following headings:-1. History2. Ore Reserves and Production Data3. Mining Methodsa. Design and Layout of the Open Cut.b. Overburden and Ore Breaking.c. Loading and Transport of Ore and Overburden.d. Transport of Men and Supplies.e. Survey and Assay.f. Drainage.4. Power and Compressed Air5. Mining Equipmenta. Shovels.b. Mine Transport.c. Dozer Tractors.d. Drill Shop.6. CostsHISTORYIn order to appreciate fully the design of the present Open Cut at Mount Morgan, a brief outline of the Mine's history and past mining methods is necessary. In 1882 the Mount Morgan Syndicate began to mine this large gold-copper orebody by small hill-top quarries...

Jan 1, 1952

By Arthur A. F, MacKenzie I. H

Copper in zinc/lead sinter charged to the Imperial Smelting Furnace operated by Sulphide Corporation Pty Limited at Cockle Creek, New South Wales, concentrates in a complex lead dross which forms as the bullion is cooled to around 400°C. The 0.35 mm portion of this dross, containing approximatelY 67 per cent of the total copper, is treated via a hydrometallurgical route to produce 5000 tonne/yr of CuSO4 5H2O crystal.Around 3000 tonne/yr of copper-lead dross containing 49 per cent copper is leached at 55°C in continuous leach reactors with ammoniacal ammonium carbonate leach liquors to convert copper to soluble copper amine complexes. Leach ettlciencies of 80-85 per cent are obtained. Leach residues are repulped with ammoniacal liquid diluents from the plant and heated in a four stage steam distillation unit to reduce ammonia levels to between 0.5 and 1.0 g/Iitre. The resultant slurry is directed to an effluent treatment plant for final treatment, and separation and return of solids to the sinter plant.Copper is extracted from leach liquor by solvent extraction techniques based on the use of L1X 54 diluted 3:1 with Shellsol 2046 to give a nominal copper loading of 30 g/litre. The loaded organic is contacted with a sulfuric acid solution of pH 5 to remove the bulk of ammonia and zinc, then stripped at 55°C with a 60 g/Iitre H2SO4 95 g/Iitre copper solution to yield a 15 g/Iitre H2SO4 125 g/Iitre copper solution.This liquor is fed to an adiabatic vacuum crvstalliser operating at 35°C and 5 kPa vacuum where crystals of CuSO4 5H2O are formed. Crystals are separated from mother liquor and washed in a two stage pusher centrifuge, then dried in a hot air rotary drier. The crystal product obtained is of a high chemical purity and readily conforms to both Australian and overseas standards.

Jan 1, 1983

By A. H. Lang

Introduction The recent uranium discovery at Theano point, lake Superior, is probably a rediscovery of the first reported Canadian uranium occurrence. A description of material from the original discovery was published in 1847 by J. L. LeConte, and many attempts have been made to relocate the deposit. Such attempts have in the past been unsuccessful because of vagueness in the original description of the locality. Besides being a prospect that seems to merit development work, the Camray discovery is important because it reaffirms the occurrence of pitchblende in the eastern part of the Precambrian shield. Much staking followed the announcement of the discovery, and some additional finds have been reported. Location The Camray discovery is at the shore of Theano point, lake Superior, about seventy miles north of Sault Ste. Marie (see Figure 1). It is in township 29, range XIV, district of Algoma. The showing is two miles from Highway No. 17, and is reached by a rough trail that leaves the highway at mileage 72.9 from Sault Ste. Marie. There are no towns of any size nearer than Sault Ste. Marie.

Jan 1, 1949

By R Salmon, C Jones

This paper examines the recent trend towards sustainability reporting and the application of the Global Reporting Initiative (GRI) æSustainability Reporting GuidelinesÆ. It also reviews reporting in the context of the Australian Minerals Industry Code for Environmental Management, as well as the status of public sustainability reporting globally in the minerals industry. The public reporting of environmental, health and safety, social/community and economic performance has evolved over the past two decades. Initially, separate and to some degree disparate documents were produced to report performance in each distinct area. In the early to mid 1980Æs some organisations had begun to report their environmental performance through some minor commentary in their annual financial reports or through ætokenisticÆ leaflets, often used as public relations exercises. Due to more media coverage and an elevated level of public scrutiny, organisations are no longer merely reporting their good performance, but also their bad and indifferent performance. In recent years these once separate environment, health and safety and community public reports have further evolved to become more integrated, reflecting organisations embarking on the reporting of their progress towards sustainable development. The primary factor in driving the evolution of sustainability reporting has been the increasing influence of stakeholders. Two groups of external stakeholders that have had a significant influence over public sustainability reporting in recent years have been non government organisations (NGOs) and socially responsible investment funds. Significant expenditure is involved in the preparation and publication of a sustainability report however many organisations do not appear to have examined in detail what they are really trying to achieve from their public reporting process. It is important to establish objectives for the public reporting process to achieve maximum benefits. Without a framework of public reporting objectives, the benefits of the reporting process to the organisation will not be recognised and the considerable expenditure involved will be increasingly difficult to justify. We believe that by focussing on the process rather than the document, significant benefits to the organisation can be gained. Indeed, with a proper framework of objectives and targets, the reporting process can be used as a vehicle to drive organisational change, implement management systems and improve performance. An idealised framework for a public sustainability reporting process sees the organisationÆs sustainability policies drive the entire process and determine the sustainability objectives. Specific targets are then set to realise those objectives. The targets will govern performance indicators that should be used to measure the success of target achievement and which will also define what data need to be collected. Evaluation is a key component of the reporting process to measure the success of target achievement and progress in realising objectives, as well as review the need for new targets to be set. The actual production of a public document is only one, albeit important, component of the overall reporting process. The challenges that lie ahead for sustainability reporting primarily relate to the integration of environmental, social and economic performance reporting as organisations integrate their approach to these areas. This will only happen as the culture of an organisation changes to not only accept the principles of sustainable development but to implement those principles in daily operations. The reporting process has the potential to drive that cultural change by communicating the organisationÆs sustainability objectives and setting challenging targets for their realisation. Public sustainability reporting will only achieve its maximum value when it forms an integral part of an organisationÆs sustainability management system and culture.

Jan 1, 2002

By L. J. Moore

Introduction Hydrometallurgical solvent extraction (SX) processes – featuring large quantities of combustible or flammable organic solvents - are common in the mining industry for recovering non-ferrous metals such as copper, nickel, cobalt, uranium, tungsten, iodine and lithium. Recent fire loss incidents and the widespread use of sub-grade tank farms and piping trenches, plastic piping, poor drainage, and closely spaced buildings demonstrate opportunities to improve the use of Inherent Safety (IS) in this industry. The mining industry has designed and constructed facilities with an emphasis on personnel safety, production efficiency and cost effectiveness. The use of IS to eliminate or minimize property fire exposures has not seen widespread practice. Lessons learned from the mainstream CPI have not been communicated or applied. As an example, copper SX plants have consistently used design of gravity flow as a cost and production-effective solution for transferring liquids and minerals through the process. In fact, Jergensen1 recommends to “utilize gravity to the fullest extent possible” in design of SX plants. This philosophy has been achieved by laying out SX plants with process equipment at different grade levels so that solutions can flow “downhill”. Because of the use of large quantities of flammable liquids and the potential for these liquids - if released – to flow unimpeded into other areas – gravity SX processes represent severe inherent fire consequences unless costly barriers, drainage and channeling are also provided. It appears that little thought has been given to the fire protection consequences and challenges of this design feature during the evolution of SX plants and most copper SX plants constructed today use some form of a sub-grade processing area (tank farm) and one-way gravity flow. While this layout is used to assure a cost effective operation it has resulted in significant exposures to high value production. The use of sub-grade production units is an inherently unsafe layout where flammable liquids are used and is a layout that would rarely if ever be used today by the mainstream CPI. Gravity-assist layout is only one example where copper SX plants have been designed and constructed without IS in mind. The use of combustible and frangible corrosion-resistant materials – such as glass, wood and plastic - for flammable liquid storage, processing and piping systems has significantly increased the hazards of these facilities. These materials of construction are not rigorous and allow for rapid failure and release of flammable contents during fire exposure. The use of combustible or frangible systems to handle or transport flammable liquids is not a practice seen today in the CPI.

Jan 1, 2006

By Robert Torbin

The objectives of the Continuous Shaft Lining (CSL) System are to reduce the costs, safety hazards, and time currently required in lining mine shafts with concrete. The CSL will line machine bored shafts downward from the shaft collar on a continuous basis using an inverted, pressurized slipforming technique. The technique for slip-forming downwards has been demonstrated and refined under this program. The approach taken involved laboratory scale testing of key features of the CSL concept. These feature tests included concrete distribution, concrete sealing, concrete slipforming and development of a reliable concrete mix. Based on these results, a full scale above-ground test facility and CSL were designed and fabricated. The objectives of these tests were to demonstrate the viability of the basic concept; to establish operating limits; and to provide input data and information for the design of a second generation shaft lining system. The results of the program have led to a CSL design and operational philosophy which will need to be tested in an underground environment before industry will accept the technology. However, the next generation CSL promises to meet all the original program technical objectives.

Jan 1, 1983

By Manuel Sanchez, Marcial Medina, Matt Hurley, Hugo Granados, Pramod Kumar, Raj Rajamani, Jose A. Delgadillo

"Large-diameter ball mills have traditionally used steel liners—steel being a highly durable material that can be shaped into any desired geometry, among which the double-wave has been the preferred design. Such a design produces a purely cascading charge motion, which is ideal for the shearing action needed to produce a finer product. Today, however, rubber liners, which have been in existence for over forty years, are now preferred over traditional steel, largely because they weigh less and are easier to maintain. In this paper, we show the operating data from the Hudbay Minerals’ Constancia Mine, wherein the liners on a 26-by-40-foot mill were changed from conventional steel liners to PolyStl™ liners. It is then shown that this change reduced the amount of energy consumed whilst being able to maintain previous grind and throughput levels. The design is verified via discrete element simulations.IntroductionThe Constancia Mine (“Our Business: Peru,” 2016) is located in the southeastern Andes of Peru, at an elevation of approximately 4,200 m. It can be accessed via the CU-126 road, about 95 km from the town of Espinar in Espinar Province. The mine also contains both the Constancia and Pampacancha deposits in the Province of Chumbivilcas. Hudbay Minerals, Inc. acquired the mine in 2011, through the purchase of Norsemont Mining, Inc. and currently retains sole ownership of the property. Production of the Constancia Mine began in 2014, with commercial production levels being achieved in April 2015.The Constancia and Pampacancha deposits primarily include hypogene, supergene, and skarn ores. The Mine’s main products, however, are copper concentrate, with silver contents, and molybdenum concentrate. These mineral reserves are expected to last approximately 22 years. Constancia’s open-pit mine supplies a processing plant that is designed for 81,900 metric tons per day of throughput. Average annual copper production is estimated to be 82,000 mT (contained metal in concentrate). Actual plant production can be found in Table 1."

Jan 1, 2017

By Michael Gauna

An evaluation and analysis of a coal pillar bump in a West Virginia mine indicated that the pillar bump occurred because of the unique combination of controlling factors. The pillar?s development stability factor of 2.6, based on Mark-Bieniawski strength and tributary loading, would typically indicate an adequate pillar size for long-term main entries. A combination of multiple-seam mining geometry and geological conditions resulted in stress concentration leading to the coal pillar bump. No high extraction mining had been performed in the area and the overlying works appeared to have adequate stability factors. However, it was interpreted that long-term flooding had softened the overlying pillar system and rendered all but the largest pillars ineffective. Contributing factors include large overlying pillars transmitting stress through the approximately 60 ft of interburden and the failed pillar?s location at a transition in the immediate roof from shale to hard, massive sandstone. Other contributing factors include sandstone channeling forcing the development section to mine the pillar smaller than surrounding pillars in an attempt to avoid the channel, the relatively high overburden of 1,100 ft, and the pillar?s position in the bottom of a trough within the coal horizon. Pillars subjected to similar conditions on the other side of the section did not fail where the roof was composed of shale, even though the roof exhibited evidence of high stress concentration. An analysis was undertaken to determine appropriate pillar size for future mining. The conditions were evaluated by investigating mine historical conditions, assessing pillar bearing pressures, and using Lamodel 2D coupled with traditional Mark-Bieniawski pillar strength and tributary area loading stability factors to determine the stress levels for the pillar. Recommendations for future pillar sizes were based on the critical load bearing capacity identified by the analysis. To date, no further pillar bumps have occurred.

Jan 1, 2008